1. Field of the Invention
Devices and manufacturing methods consistent with the present invention relate to a micro switch device and a micro switch device manufacturing method which can be used for a radio frequency (RF) antenna module and the like.
2. Description of Related Art
A switch having a micro structure may be used in a multi-band or a module of a multi-mode, and also may be used in various bands since the switch having the micro structure has a feature of a low loss within 1 dB, and has an isolation greater than approximately 40 dB in all bands within approximately 10 GHz, including a direct current (DC). In addition, in an RF device, the switch having the micro structure may be used to manufacture a switch, a switchable varactor, and an inductor, and may be used as a basic antenna.
FIG. 1 is a perspective view illustrating a related art micro switch device 1, and FIG. 2 is a front view illustrating the micro switch device 1 of FIG. 1.
Referring to FIGS. 1 and 2, the related art micro switch device 1 includes a substrate 10, a driving stage 20 on the substrate 10, a spring 30, fixed electrodes 52 and 54, an input terminal 62, and an output terminal 64. The driving stage 20 is located on a top of the substrate 10, and the driving stage 20 is supported by the spring 30 which is expanded from four corners. Since ends of the spring 30 are supported by an anchor 32, the driving stage 20 may be spaced apart from the top of the substrate 10, and may be horizontally fixed.
The driving stage 20 includes the driving electrodes 22 and 24 on both sides of the driving stage 20, and includes a connection point 26 between the driving electrodes 22 and 24. The fixed electrodes 52 and 54 are located on a bottom of the driving electrodes 22 and 24, and the input terminal 62 and the output terminal 64 are located on a bottom of the connection portion 26 for switching.
The micro switch device 1 is generally used for an RF module, and in the micro switch device 1, the driving stage 20 moves in a vertical direction of the substrate 10 by an electrostatic force between the fixed electrodes 52 and 54 and the driving electrodes 22 and 24. In this instance, when the driving stage 20 moves to the substrate 10, the connection portion 26 is contacted to both the input terminal 62 and the output terminal 64 to allow an electric current between the terminals.
Referring to FIG. 2, the driving stages 20 on the substrate of the micro switch device 1 are spaced apart from each other by a predetermined distance by the anchors 32, and the connection portion 26 of both of the anchors 32 is suspended by both of the springs 30.
Generally, an entire driving stage 20 elastically deforms so that the connection portion 26 may connect the input terminal 62 with the output terminal 64. As illustrated in FIGS. 1 and 2, an elastic deformation occurs in both the driving stage 20 and the spring 30 so that the connection portion 26 connects the input terminal 62 with the output terminal 64, and the electrostatic force between the fixed electrodes 52 and 54 and the driving electrodes 22 and 24 may move the connection portion 26 to the input terminal 62 and the output terminal 64 since the electrostatic force is greater than an elastic resilience with respect to the elastic deformation. As the elastic resilience by the driving stage 20 and the spring 30 is large, a greater voltage difference is required to be supplied between the driving electrodes 22 and 24 and the fixed electrodes 52 and 54, and this may decrease reliability and efficiency of the micro switch device 1.
In addition, a distance between the driving stage 20 and the fixed electrodes 52 and 54 is an important issue when manufacturing the micro switch device 1. If the driving stage 20 and the fixed electrodes 52 and 54 are relatively close to each other, the micro switch device 1 may operate at a comparatively lower voltage. Conversely, if the driving stage 20 and the fixed electrodes 52 and 54 are relatively far from each other, the micro switch device 1 may not properly operate even when a higher voltage is supplied. Under other circumstances, the micro switch device may not properly operate due to residual substance such as dust, and the like, between the driving electrodes 22 and 24 and the fixed electrodes 52 and 54.